US9103771B2 - Device for quantifying the degassing of a piece of equipment arranged in a vacuum chamber - Google Patents

Device for quantifying the degassing of a piece of equipment arranged in a vacuum chamber Download PDF

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Publication number
US9103771B2
US9103771B2 US13/634,384 US201113634384A US9103771B2 US 9103771 B2 US9103771 B2 US 9103771B2 US 201113634384 A US201113634384 A US 201113634384A US 9103771 B2 US9103771 B2 US 9103771B2
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Prior art keywords
blade
free end
oscillation frequency
quantification
vacuum chamber
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US20130000402A1 (en
Inventor
Alain Bettacchioli
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Thales SA
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Thales SA
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G01N29/2412—Probes using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
    • G01N5/04—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0254—Evaporation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0256—Adsorption, desorption, surface mass change, e.g. on biosensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0427—Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
    • G01N9/36—Analysing materials by measuring the density or specific gravity, e.g. determining quantity of moisture

Definitions

  • the present invention relates to a device for quantifying the degassing of a piece of equipment placed in a vacuum chamber. It applies notably to the field of equipment tests in a vacuum environment and more particularly to the vacuum degassing tests of space equipment for satellites.
  • the quartz crystal microbalance serves to obtain are only satisfactory if the mass of the deposit collected is very low, typically less than about a hundred micrograms per cm 2 , so that when a clearly identified substance is deposited as a uniformly ordered layer, it is possible to determine the thickness of the deposit therefrom.
  • the determination of the deposit thickness is only important in the context of the semiconductor industry which must take deposit thicknesses into consideration during metallization, oxidation or epitaxy processes, for example. In this case, the deposit thickness never exceeds a few hundred Angströms. On the contrary, during degassing tests under thermal vacuum, this thickness evaluation is less important and it is more advantageous to quantify the mass of pollutant deposited per unit area at various points of the system under test.
  • the device for quantifying the degassing of a piece of equipment placed in a vacuum chamber comprises a metal blade made from a ferromagnetic material comprising a fixed end and a free end, the blade being provided with a cooling device and a device for measuring the intrinsic temperature of the blade, an electromagnet for exciting the blade, a measurement sensor for measuring the excitation of the free end of the blade connected to a device for acquiring measurements and for calculating at least one oscillation frequency of the free end of the blade, the acquisition and calculation device being connected to a device for calculating the surface density of a mass deposited on the blade.
  • the electromagnet comprises a periodically powered coil.
  • the senor for measuring the excitation of the free end of the blade may consist of a magnet placed opposite the free end of the blade and a coil, the magnet being placed at the center of the coil.
  • the senor for measuring the excitation of the free end of the blade may consist of one or two magnets placed directly on the fixed end of the blade and a coil placed opposite the free end of the blade.
  • the device for acquiring the oscillation frequency of the free end of the blade comprises an analog-to-digital converter and a fourth-order Chebyshev filter.
  • the quantification device further comprises a device for determining the oscillation frequency of the blade alone in the vacuum chamber for a blade temperature value identical to that corresponding to the blade of which the oscillation frequency is measured.
  • the device for determining the oscillation frequency of the blade alone comprises a calibration curve of the oscillation frequency of the blade alone as a function of the blade temperature.
  • the blade temperature can be controlled by means of one or two peltier effect modules.
  • the oscillation frequency of the blade alone can be corrected as a function of the residual pressure in the caisson when said pressure exceeds 10 ⁇ 3 hectopascals.
  • FIG. 1 a schematic side view of an example of a device for quantifying the degassing of a piece of equipment under vacuum, according to the invention
  • FIG. 2 an example of a chronogram illustrating the acquisition of measurements of the device, according to the invention
  • FIG. 3 a schematic plan view of the degassing quantification device in FIG. 1 , according to the invention
  • FIG. 4 a schematic side view of an alternative embodiment of the device for quantifying the degassing of a piece of equipment under vacuum, according to the invention
  • FIG. 5 a schematic plan view of the degassing quantification device of FIG. 4 , according to the invention.
  • the invention therefore consists in measuring the quantity of pollutants deposited on a cold surface consisting of a cooled blade. Due to the solidification temperature of the polluting particles, for example such as water, of which the solidification point is close to 0° C. between atmospheric pressure and 6 hectopascals, to ⁇ 74° C. approaching 10 ⁇ 3 hectopascals and about ⁇ 110° C. approaching 10 ⁇ 6 hectopascals, the blade temperature must be lower than this lowest temperature value of ⁇ 110° C.
  • the device for quantifying the degassing of a piece of equipment under vacuum shown in FIGS. 1 and 3 to 5 is intended to be placed inside a vacuum chamber in the presence of the equipment to be tested.
  • the device comprises a flexible stainless metal blade 10 having ferromagnetic properties, that is to say, a magnetic permeability higher than 0.1, for example, a steel foil containing 0.1% to 2% carbon.
  • the blade 10 may have a thickness of about a tenth of a millimeter, a standard width of 12.7 mm and a length of about 15 cm.
  • the blade 10 comprises a fixed end 11 attached to a fixed support, not shown, and a free end 12 .
  • the blade 10 is provided with a cooling device 13 and with a device for measuring its intrinsic temperature, for example a thermocouple.
  • the device 13 for cooling the blade 10 may, for example, comprise a thermal braid connecting the fixed support to a cold source inside the vacuum chamber, or one or two peltier effect modules pressed against the blade, supplied with electricity and thermally connected, for example, by thermal braids 30 , to a cold source which serves to remove the heat that they release.
  • An electromagnet 15 which can be placed next to the blade 10 , serves to excite the blade 10 .
  • the electromagnet 15 comprises a coil powered periodically, the period T being for example equal to one minute, by an electric current pulse having a duration T 1 of a few tenths of a second. Under the effect of the electric pulse, the free end 12 of the blade oscillates freely at an oscillation frequency which depends on its mass.
  • the higher the mass of the blade the lower its oscillation frequency.
  • the oscillation frequency of the clean blade and the oscillation frequency of the blade By measuring the oscillation frequency of the clean blade and the oscillation frequency of the blade during the degassing test of the equipment under vacuum, it is therefore possible to determine the mass of pollutant deposited per unit area on the blade 10 .
  • the oscillation frequency of the blade 10 also depends on its temperature due to the variation in its Young's modulus as a function of temperature, it is necessary to make a preliminary calibration to plot a curve of the variation of the frequency of the clean blade as a function of its temperature. The calibration is made under vacuum for various temperatures of the blade alone, in the absence of any equipment in the vacuum chamber, and the calibration curve obtained is recorded.
  • the oscillation frequency of the blade 10 is measured using a coil 16 comprising a large number of turns, for example about 10,000 turns. Since the cooled blade 10 is ferromagnetic, its free end is magnetized either by influence with a permanent magnet 17 placed at the center of the coil as shown in FIGS. 1 and 3 , or by one or two magnets 13 pressed against the blade 12 as shown in FIGS. 4 and 5 .
  • the coil 16 provided or not provided with a central permanent magnet 17 , is placed in front of the free end 12 of the blade 10 . Since the cooled blade 10 is ferromagnetic, the permanent magnet 17 influences the blade of which the free end is magnetized.
  • the magnetized blade When the magnetized blade oscillates, it generates an electromotive force at the terminals of the coil 16 by Lenz effect.
  • the electromotive force at the terminals of the coil 16 has a voltage value which varies as a function of the movement of the magnetized end of the blade and hence as a function of the oscillation frequency of the blade 10 .
  • the voltage across the terminals of the coil 16 is measured after a latency period T 2 following the excitation of the blade, for example T 2 may be about one second, thereby serving to overcome a transition period during which the oscillation regime is established and to avoid undesirable effects that would disturb the estimation of the blade oscillation frequency.
  • the output of the measurement amplifier 19 is connected to a measurement acquisition device 20 comprising an analog-to-digital converter for digitizing the amplified signal and a low-pass filter for selecting a particular oscillation mode and for eliminating the other modes.
  • the mode selected may be the first mode, that is to say, the principal mode.
  • the filter selected may, for example, be a fourth-order Chebyshev filter comprising cutoff frequencies located at 60% of the central frequency of the filter on either side of this central frequency.
  • the digitized signal is transmitted to a device 21 for calculating the oscillation frequency of the polluted blade.
  • the temperature of the blade 10 can be acquired for example on the expiration of the duration T 3 corresponding to the acquisition of the voltage measurements.
  • the thermocouple placed on the blade is connected to a device 22 for acquiring the temperature of the blade.
  • the thermocouple must be electrically isolated from the blade and, for this purpose, it is placed either between two pellets of adhesive kapton having a maximum diameter of 5 mm, or maintained on the blade by a spot of silicon glue.
  • the output of the temperature acquisition device 22 is connected to a device 23 for determining the frequency of the clean blade corresponding to this temperature.
  • the frequency of the clean blade is determined from the calibration curve prepared in the preliminary calibration step.
  • the oscillation frequencies of the polluted blade and of the clean blade corresponding to the same blade temperature are transmitted to a device 24 for calculating the surface density of the mass deposited on the blade 10 .
  • the surface density ⁇ of the mass deposited on the blade is obtained from the following equation:
  • ⁇ ⁇ ⁇ [ [ f m ⁇ ( T ) ] 2 [ f 0 ⁇ ( T ) ] 2 - 1 ]
  • ⁇ is the mass deposited per unit area
  • f 0 is the oscillation frequency of the clean blade at temperature T
  • f m is the oscillation frequency of the polluted blade at temperature T
  • ⁇ is a calibration coefficient

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Electromagnetism (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
  • Measuring Fluid Pressure (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
US13/634,384 2010-03-12 2011-02-28 Device for quantifying the degassing of a piece of equipment arranged in a vacuum chamber Active 2032-02-28 US9103771B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR1001001A FR2957416B1 (fr) 2010-03-12 2010-03-12 Dispositif de quantification du degazage d'un equipement place dans une enceinte a vide
FR1001001 2010-03-12
PCT/EP2011/052906 WO2011110437A1 (fr) 2010-03-12 2011-02-28 Dispositif de quantification du dégazage d'un équipement placé dans une enceinte à vide

Publications (2)

Publication Number Publication Date
US20130000402A1 US20130000402A1 (en) 2013-01-03
US9103771B2 true US9103771B2 (en) 2015-08-11

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Country Status (8)

Country Link
US (1) US9103771B2 (fr)
EP (1) EP2545355B1 (fr)
JP (1) JP5796259B2 (fr)
BR (1) BR112012023032B1 (fr)
CA (1) CA2792664C (fr)
ES (1) ES2445805T3 (fr)
FR (1) FR2957416B1 (fr)
WO (1) WO2011110437A1 (fr)

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
EP2883798B1 (fr) * 2013-12-12 2017-06-28 Airbus DS GmbH Procédé de calcul du processus d'auto-contamination d'un engin spatial
US9683954B2 (en) * 2014-01-27 2017-06-20 Sreeram Dhurjaty System and method for non-contact assessment of changes in critical material properties
CN106347718B (zh) * 2016-11-08 2019-05-07 中国科学院空间应用工程与技术中心 一种服务于高微重力科学实验的隔振平台

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2602589A1 (fr) 1986-08-06 1988-02-12 Matra Procede et dispositif de mesure de masse en apesanteur
US4884446A (en) * 1987-03-12 1989-12-05 Ljung Per B Solid state vibrating gyro
US5684276A (en) 1995-12-12 1997-11-04 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Micromechanical oscillating mass balance
US6041642A (en) * 1998-06-04 2000-03-28 Lockheed Martin Energy Systems, Inc. Method and apparatus for sensing the natural frequency of a cantilevered body

Family Cites Families (7)

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US4418774A (en) * 1981-12-08 1983-12-06 Franklin Electric Co., Inc. Weight or force measuring apparatus
US5488203A (en) * 1993-11-05 1996-01-30 Rupprecht & Patashnick Company, Inc. Force compensator for inertial mass measurement instrument
JP3844784B2 (ja) * 1997-09-08 2006-11-15 日本碍子株式会社 圧電／電歪デバイス
JP2005274164A (ja) * 2004-03-23 2005-10-06 Citizen Watch Co Ltd バイオセンサー装置
JP2007010518A (ja) * 2005-06-30 2007-01-18 Canon Inc カンチレバーセンサを利用するターゲット物質の検出方法及び検出装置
JP4713459B2 (ja) * 2006-12-25 2011-06-29 日本電波工業株式会社 感知装置
JP5093685B2 (ja) * 2008-08-08 2012-12-12 独立行政法人産業技術総合研究所 プラズマ装置の供給ガス分解率測定装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2602589A1 (fr) 1986-08-06 1988-02-12 Matra Procede et dispositif de mesure de masse en apesanteur
US4884446A (en) * 1987-03-12 1989-12-05 Ljung Per B Solid state vibrating gyro
US5684276A (en) 1995-12-12 1997-11-04 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Micromechanical oscillating mass balance
US6041642A (en) * 1998-06-04 2000-03-28 Lockheed Martin Energy Systems, Inc. Method and apparatus for sensing the natural frequency of a cantilevered body

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Classic Filters, http://194.81.104.27/~brian/DSP/ClassicFilters.pdf, Accessed Oct. 29, 2014. *
Classic Filters, http://194.81.104.27/˜brian/DSP/ClassicFilters.pdf, Accessed Oct. 29, 2014. *
English Translation of FR 2602589, Feb. 12, 1988. *

Also Published As

Publication number Publication date
FR2957416A1 (fr) 2011-09-16
JP2013522583A (ja) 2013-06-13
BR112012023032A8 (pt) 2017-10-17
BR112012023032B1 (pt) 2020-04-28
BR112012023032A2 (pt) 2016-05-17
EP2545355B1 (fr) 2013-12-18
JP5796259B2 (ja) 2015-10-21
ES2445805T3 (es) 2014-03-05
CA2792664C (fr) 2018-09-04
EP2545355A1 (fr) 2013-01-16
CA2792664A1 (fr) 2011-09-15
US20130000402A1 (en) 2013-01-03
FR2957416B1 (fr) 2012-04-20
WO2011110437A1 (fr) 2011-09-15

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